Handling Facility and Ventilation Device

ABSTRACT

An arranging facility, a parking facility, a handling facility, and a ventilation device. A vehicle maintenance facility as the arranging facility comprises a vehicle maintenance booth as an arranging space and a forcible air supply/discharge mechanism. The vehicle maintenance booth is surrounded by side walls and a ceiling wall as partition walls on its periphery. A maintenance vehicle on which a fuel battery as an energy converter is mounted is temporarily disposed in the vehicle maintenance booth. Also, the air supply/discharge mechanism comprises an air intake device feeding air to the vehicle maintenance booth and an air discharge device discharging the air from the vehicle maintenance booth to dilute hydrogen gas leaking from a vehicle under maintenance.

This is a 371 national phase application of PCT/JP2006/308253 filed 13Apr. 2006, claiming priority to Japanese Patent Application No.2005-116458 filed 14 Apr. 2005, the contents of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to a facility for temporarily arranging afuel-cell electric vehicle that uses an inflammable gas and on which afuel cell is mounted, and for performing handling work of such a device.

BACKGROUND OF THE INVENTION

Devices utilizing a fuel cell including fuel-cell electric vehicles havebeen vigorously developed. Since a strongly inflammable gas such ashydrogen is generally used in the fuel cell as a fuel gas, due attentionshould be paid to leakage of gas out of the device when performing anexperiment, production, maintenance, or inspection of a device using thefuel cell.

Japanese Patent Application Laid-Open No. 10-310033 discloses atechnology for an inspecting facility for carrying out an inspection inan inspection room in which a general vehicle is enclosed by walls.However, the document discloses no technology regarding measures toprevent gas leakage.

Japanese Patent Application Laid-Open No. 5-180478 discloses atechnology to enhance collection efficiency of exhaust gas by providingair intake ports on the ceiling and air discharge ports on the floorsurface of a closed terminal for vehicles (such as a bus terminal or atruck terminal) or a closed parking garage (such as an undergroundparking garage). Also, Japanese Patent Application Laid-Open No.2005-98616 discloses a configuration in which two cross flow fans arearranged vertically side by side and mutual air blowing directions areset so that air currents merge together in order to efficiently provideventilation in an indoor parking garage. However, technologies of thesedocuments are intended only for exhaust gases and do not assume gasleakage from fuel-cell electric vehicles.

Japanese Patent Application Laid-Open No. 2005-353346 discloses atechnology for providing ventilation by determining a hydrogenconcentration in a closed facility such as an underground parking garagewhere fuel-cell electric vehicles are parked or stopped, from thehydrogen concentration or an amount of decrease in hydrogen of vehiclesand the volume and ventilation capabilities of the facility. However,this document describes as a ventilator only a configuration for simplyproviding a fan on the ceiling.

For example, a fuel-cell electric vehicle comprises many components,including, for example, a pipe for fuel gas, and has a complicatedstructure. Since it is difficult, in particular, to prevent gas leakagefrom a joint between components in the course of inspection/maintenancework, operators perform inspection/maintenance work with the greatestcare.

However, when fuel-cell electric vehicles come into widespread use inthe near future, it is anticipated that vehicle maintenance work thereofwill be done in the same manner as for current gasoline-engine vehicles.Thus, it is desirable to prepare an inspection/maintenance facility forwhich measures for preventing gas leakage that could ensure safetysufficiently are taken even when an operator performs ordinarymaintenance work. There is a great necessity for introducing atechnology for preventing gas leakage, particularly when a gas iscolorless and odorless such as hydrogen gas and an operator himself(herself) cannot detect gas leakage. Moreover, in view of introductioncosts, it is desirable to be able to realize such aninspection/maintenance facility by developmentally expanding aconventional inspection/maintenance facility.

It is also effective to establish the technology for preventing gasleakage to be introduced to an inspection/maintenance facility in aclosed-space facility in which fuel-cell electric vehicles are parked orstored such as a residential garage, an underground parking garage, or amultistory parking garage. This is because simple maintenance work isperformed also in such a facility and gas leakage could occur there.

These points are challenges faced not only by fuel-cell electricvehicles, but also by the fuel cell itself and by other devices on whichthe fuel cell is mounted. Similar measures are also demanded for devicesthat contain a power mechanism using an inflammable gas (for example,hydrogen, propane gas, or natural gas) such as a vehicle having aninternal combustion engine using an inflammable gas.

SUMMARY OF THE INVENTION

An object of the present invention is to introduce a technology forpreventing gas leakage to a facility in which fuel-cell electric vehicleon which a fuel cell is mounted is temporarily arranged and which issubjected to handling work.

Another object of the present invention is to introduce a technologyregarding a function for preventing gas leakage to a facility in which afuel-cell electric vehicle on which a fuel cell is mounted istemporarily arranged and which is subjected to at least one ofexperiment, production, inspection, and maintenance.

Still another object of the present invention is to establish a simplemode in which an inspection/maintenance facility for conventionalgasoline-engined vehicles is modified to one for vehicles using aninflammable gas.

A reference arranging facility in the present invention includes anarranging space whose periphery is surrounded by partition walls and inwhich an energy converter using an inflammable gas as a fuel or a deviceon which the energy converter is mounted is temporarily and arrangeablydisposed, and a forcible gas supply/discharge mechanism that dilutes theinflammable gas leaking out of the energy converter into the arrangingspace by supplying a diluent gas to the arranging space and dischargingthe inflammable gas from the arranging space.

The inflammable gas is a gas that exists as a gas at room temperatureand atmospheric pressure and is easily inflammable by combining withoxygen and more specifically refers to hydrogen, methane, propane,natural gas, and the like. The energy converter includes a fuel cell(including reformers for providing an inflammable gas to the fuel celland fuel cell unit/assembled stacks) that extracts electric energy byallowing chemical reaction of such an inflammable gas, or an internalcombustion engine that extracts kinetic energy by causing an inflammablegas to be subjected to combustion, such as a hydrogen fueled engine or acompressed natural gas (CNG) engine, as well as pipes, valve mechanisms,and the like of fuel gases used for such a fuel cell or internalcombustion engine. It is assumed that devices on which an energyconverter is mounted include, in addition to floor-type devices, mobiledevices such as vehicles, ships, aircraft, mobile robots, and mobileelectronic devices.

Temporarily arranging signifies that, instead of arranging permanently,for example, arranging for a limited period such as an hour, a day, aweek, or a month. However, the closing period need not be defined. In anarranging facility, a process in which an energy converter or a mountingdevice thereof is arranged in an arranging space and then removed fromthe arranging space will be performed repeatedly.

A reference parking facility in the present invention is a spaceconverted from the arranging space in the arranging facility so thatfuel-cell electric vehicles in which a fuel cell serving as an energyconverter is mounted are temporarily stored or parked. Examples of theparking facility include a residential garage in which one or two tothree fuel-cell electric vehicles can be parked, and an undergroundparking garage or multistory parking garage which can accommodate manyfuel-cell electric vehicles (for example, 10 or more vehicles, or 100 ormore vehicles for a large-scale parking garage).

A handling facility in the present invention is a work booth convertedfrom the arranging space in the arranging facility to enable handlingwork of a fuel-cell electric vehicle, which is a device on which a fuelcell is mounted as an energy converter. Incidentally, components andmodification modes will be described below with the handling facility inmind, but such descriptions can be applied to the arranging facility andthe parking facility in substantially the same manner.

Handling work of a device refers to work such as performing anexperiment involving the device, or manufacturing, inspecting, ormaintaining the device. The booth is used as a term referring to a spaceseparated from surroundings by partition walls. Therefore, the workbooth refers to a work space separated from an external space bypartition walls to perform handling work; in other words, a work roomfor handling work. Partition walls constitute boundaries for separatingthe work space inside the work booth from the external space. Partitionwalls also include vertically or obliquely arranged sides and obliquelyor horizontally arranged ceiling surfaces and floor surfaces. Partitionwalls need not necessarily seal a work space hermetically and may havean opening such as a port for inserting and taking out an energyconverter, or a ventilation opening for realizing natural ventilation.

The gas supply/discharge mechanism is a mechanism for forcibly providingventilation inside the work booth by using mechanical power, such as bymeans of a fan or by means of releasing a compressed gas stored in a gascylinder. A process forcibly performed may be only supply, onlydischarge, or both the supply and discharge. As the diluent gas theremay be used, for example, a non-inflammable gas/inert gas such asnitrogen and helium, or air.

According to the configuration, there can be realized a handlingfacility (such as an inspection/maintenance facility, a manufacturingfacility, or a laboratory facility) that quickly dilutes an inflammablegas leaked from an energy converter into a work booth and discharges gasfrom the work booth. Therefore, safety can be sufficiently ensured inthe work booth even when a gas leak occurs. In addition, this technologycan also be implemented in a facility shown in the above Patent Document1 by introducing a gas supply/discharge mechanism, providing anadvantage of simple introduction at low cost.

In an aspect of the handling facility of the present invention, theinflammable gas is a gas lighter than the diluent gas, and the gassupply/discharge mechanism supplies the diluent gas from below a workbooth (for example, below the arranging position of an energy converter)and the gas is discharged from above the work booth. In this case, theinflammable gas in the diluent gas rises due to convection caused by adensity difference. Therefore, in consideration that it is desirable notto reverse the flow of this natural convection, the flow of diluent gasis set from below upward. A discharge from above the work boothtypically refers to a discharge from the ceiling surface of partitionwalls. Supplying from below the arranging position of an energyconverter is implemented, for example, by supplying from the floorsurface. If, in this configuration, the diluent gas is different from agas filling the work booth during the course of normal work (normallyair), it is particularly desirable that the inflammable gas is lighterthan the gas filling the work booth, in order to quickly discharge theinflammable gas. If the diluent gas (and the gas filling the work boothduring normal work) are lighter than the inflammable gas, the gassupply/discharge mechanism may be set to supply the diluent gas fromabove the arranging position of an energy converter and the gas isdischarged from below the work booth (such as from the floor surface).

In another aspect of the handling facility of the present invention,there are provided an inflammable gas sensor for detecting aninflammable gas having leaked into the work booth, and a control devicefor controlling supply or discharge of the gas supply/dischargemechanism in accordance with a detection result of the inflammable gassensor. The inflammable gas sensor is a sensor for detecting whether anyinflammable gas is present, as well as a concentration thereof. Theinflammable gas sensor is desirably set up on a side to which theinflammable gas is likely to flow and also near a region where a gas islikely to be condensed (accumulated). If, for example, the inflammablegas is lighter than a surrounding gas and the diluent gas supplied bythe gas supply/discharge mechanism does not flow or flows slowly, theinflammable gas sensor may be provided in an upper part of the workbooth (may be within the work booth or within an air discharge duct orthe like led from the work booth). It is also effective, if necessary,to devise a method of preventing a detection error by making the gaspassage thinner or stirring the gas by a fan or the like in the vicinityof the inflammable gas sensor. From the viewpoint of enhancingdetectability, it is also effective to provide a plurality ofinflammable gas sensors.

In another aspect of the handling facility of the present invention, ifan inflammable gas satisfying a predetermined condition is detected, thecontrol device activates the gas supply/discharge mechanism. That is,the supply/discharge mechanism is set so that the gas supply/dischargemechanism is not normally activated, but if an inflammable gas isdetected (at a level equal to or greater than a set value), the gassupply/discharge mechanism is activated to quickly discharge the gas.This configuration is effective in realizing energy conservation and asilent environment. Also, when handling work of a device using noinflammable gas and that of a device using an inflammable gas areperformed in combination, the present configuration in which the gassupply/discharge mechanism is activated only when necessary functionseffectively.

In another aspect of the handling facility of the present invention, aninclined-face structure accumulating an inflammable gas that rises orfalls due to a density difference from the gas filling the work boothduring the course of normal work is provided in an upper part or lowerpart of the work booth and the inflammable gas sensor detects theaccumulated inflammable gas. The inclined-face structure refers to astructure having an inclined face for guiding and accumulating aconvecting inflammable gas. The inclined-face structure may be formedusing partition walls or a floor surface or separately from them.Although no particular limitation is imposed on the shape of theinclined face, if the inclined face has a two-dimensional curve likethat of a funnel, horizontal motion can be controlled toward one point,increasing the degree of condensation of the inflammable gas. Theinflammable gas concentrated in this way may be discharged by means ofthe gas supply/discharge mechanism, but also may be discharged usingnatural convection (for example, by simply providing a discharge port inan upper part or a lower part) without using the gas supply/dischargemechanism.

In another aspect of the handling facility of the present invention, ifan inflammable gas satisfying the predetermined condition is detected,the control device increases supply and discharge amounts by the gassupply/discharge mechanism. That is, if an inflammable gas is detected(at a level equal to or greater than a set value), the amount ofventilation is increased. Switching to an increase may be one-step, ormulti-step or infinite-step in accordance with the amount of gas.

In another aspect of the handling facility of the present invention, thegas supply/discharge mechanism has a plurality of supply ports providedat mutually different positions or a plurality of exhaust ports providedat mutually different positions and, if an inflammable gas satisfyingthe predetermined condition is detected, among the plurality of supplyports or exhaust ports, the control device changes a combination ofsupply ports or exhaust ports to be activated. Typically, if aninflammable gas is detected (at a level equal to or greater than a setvalue), the number of supply ports or exhaust ports is increased. As aresult of this, it becomes possible to increase the flow rate of gas andto change the flow direction of gas, thereby promoting ventilation. Anexample of changing the direction includes a mode in which the flow setin the vertical direction normally by supplying and discharging throughthe floor surface and ceiling surface of the work booth is changed tothe horizontal direction by supplying and discharging through oppositesides of the work booth. Another example is a mode example in which, ifthe handling work facility is huge, a pattern of supply ports or exhaustports to be activated is changed to enhance ventilation efficiency in adetection target range of sensors satisfying the predetermined conditionamong a plurality of disposed sensors.

In another aspect of the handling facility of the present invention, thegas supply/discharge mechanism includes a circuit for resupplying atleast a portion of the gas discharged from the work booth to the workbooth and, if an inflammable gas satisfying the predetermined conditionis detected, the control device suppresses or stops a gas circulation.That is, if no inflammable gas is detected (at a level equal to orgreater than a set value), at least a portion of the gas is circulated(after providing any necessary treatment to remove any inflammable gas).However, when an inflammable gas is detected (at a level equal to orgreater than a set value), a dilution effect shall be enhanced byreducing the amount of circulation or setting the amount of circulationto 0 to thereby allow a new diluent gas to flow in.

In another aspect of the handling facility of the present invention, avehicle on which an energy converter is mounted is inspected andmaintained in the work booth.

A ventilation device in the present invention is a device that includesthe gas supply/discharge mechanism provided in the handling facility.The ventilation device may also be formed as a device by separatelymounting a plurality of components in any of these facilities. When thegas supply/discharge mechanism is controlled by the control device, theventilation device includes its control device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a configuration outline of a vehiclemaintenance facility according to an embodiment of the presentinvention;

FIG. 2 is a diagram showing an example control mode of the vehiclemaintenance facility of FIG. 1;

FIG. 3A is a diagram showing a ventilation mode of the vehiclemaintenance facility according to a modification;

FIG. 3B is a diagram showing the ventilation mode of the vehiclemaintenance facility according to the modification; and

FIG. 4 is a schematic view showing the configuration outline of thevehicle maintenance facility according to another modification.

DETAILED DESCRIPTION

A typical embodiment of the present invention will be described below.In the descriptions that follow, a facility for maintaining vehicles onwhich a fuel cell using hydrogen (and oxygen in the air) as a fuel ismounted is taken as an example. Here, hydrogen is an inflammable gas andthe fuel cell is an energy converter that extracts electric energythrough chemical reaction of hydrogen. However, needless to say, thepresent invention can also be applied in the same manner to otherinflammable gases and energy converters such as internal combustionengines. It is also evident that the present invention can be appliednot only to inspection/maintenance facilities (equipment), but also tolaboratory facilities (equipment) and manufacturing facilities(equipment).

FIG. 1 is a schematic view showing a configuration outline of a vehiclemaintenance facility 10 according to the present embodiment. The vehiclemaintenance facility 10 includes, as its main components, a vehiclemaintenance booth 20, an air intake device 30, an air discharge device40, a duct 50, a hydrogen sensor 80, and a control device 90.

The vehicle maintenance booth 20 is a work booth of a rectangularparallelepiped shape and therein, inspection/maintenance work on amaintenance vehicle 110 set to a work position is performed. Theperiphery of a work space 22, which is an inner part of the vehiclemaintenance booth 20, is surrounded by side walls 24 and a ceiling wall26 serving as partition walls. Many fine vent holes are provided on afloor surface 28.

The air intake device 30 is a device provided by the side of the vehiclemaintenance booth 20 and supplies air to the vehicle maintenance booth20 by means of an internal fan 32. The air discharge device 40 is adevice consisting of air discharge sections 42, 44, and 46 mounted onthe upper side of the ceiling wall 26 of the vehicle maintenance booth20. In each of the air discharge sections 42, 44, and 46, an airdischarge port and a fan are provided to discharge, together with air,hydrogen leaking from the maintenance vehicle 110.

The duct 50 constitutes a flow channel of air outside the vehiclemaintenance booth 20. The duct 50 includes an air discharge duct 52, anexhaust port 54, a circulating duct 56, an intake 58, and a supply duct60. One end of the air discharge duct 52 is connected to the airdischarge device 40 and the other end is connected to the exhaust port54 to lead air discharged from the vehicle maintenance booth 20 to theoutside. One end of the circulating duct 56 is connected to anintermediate part of the air discharge duct 52 and the other end isconnected to the air intake device 30 to form a channel for resupplyingdischarged air. The intake 58 is provided in an intermediate part of thecirculating duct 56. If air is fed to the air intake device 30 from theintake 58 instead of the air discharge duct 52, fresh air will besupplied to the vehicle maintenance booth 20. One end of the supply duct60 is connected to the air intake device 30 to lead air to below thefloor surface 28 of the vehicle maintenance booth 20. As has beendescribed, many fine vent holes are provided on the floor surface 28 andair is supplied from the supply duct 60 to the vehicle maintenance booth20 through these vent holes.

Dampers 70, 72, and 74 are provided in the duct 50 as movable plates forcontrolling the flow of air. The damper 70 is provided between branchingto the circulating duct 56 and the exhaust port 54 in the air dischargeduct 52 to adjust the amount of circulation and that of discharge to theoutside. The damper 72 is provided between branching from the airdischarge duct 52 and the intake 58 in the circulating duct 56 to adjustthe amount of circulation. Then, the damper 74 is provided at the intake58 to adjust the amount of intake of fresh air. These dampers 70, 72,and 74 constitute, together with the air intake device 30, the airdischarge device 40, and the duct 50, the gas supply/discharge mechanismto realize ventilation of the vehicle maintenance booth 20.

The hydrogen sensor 80 is a gas sensor disposed in the air dischargeduct 52 and can detect the amount of hydrogen.

The control device 90 is a computer device for controlling airconditioning of the vehicle maintenance facility 10. The device can beformed by specifying operations of hardware such as a personal computer(PC) and microcomputer having operation/storage functions using software(programs). The control device 90 includes an input/output section 92, acomparison section 94, and a threshold table 96. The input/outputsection 92 acquires output data of the hydrogen sensor 80 before sendingthe output data to the comparison section 94 and also sends operationinstruction signals to the fan 32 of the air intake device 30, the airdischarge device 40, and the dampers 70, 72, and 74 according toinstructions of the comparison section 94. After acquiring the amount ofdetected hydrogen from the input/output section 92, the comparisonsection 94 determines an optimal control state with reference to thethreshold table 96. Then, the comparison section 94 instructs theinput/output section 92 to send a control signal to realize thedetermined control state.

Subsequently, operations of the vehicle maintenance facility 10 will bedescribed with reference to FIG. 1 and FIG. 2. Like FIG. 1, FIG. 2 is adiagram showing the vehicle maintenance facility 10, and like referencenumerals are assigned to like components, and repeated descriptions areomitted.

As shown in FIG. 1, the maintenance vehicle 110 on which a fuel cell ismounted is brought into the work space 22 inside the vehicle maintenancebooth 20 before being set to the work position. Using equipment andtools (not shown) provided in the work space 22, an operator performsvarious kinds of inspection/maintenance work.

At least when performing work related to the fuel cell, the operatormanipulates the control device 90 to activate an air conditioning systeminside the vehicle maintenance booth 20. That is, the air intake device30 and the air discharge device 40 are set to ON to allow a small amountof air in the work space 22 to flow from the floor surface 28 toward theceiling wall 26. At this point, the damper 70 is set to a slightly openstate so that approximately 10% of discharged air is discharged to theoutside. The damper 72 is maintained in a completely open state tomaintain a smooth flow of circulation. The damper 74 is also set to aslightly open state to take in approximately 10% of air from outsidethrough the intake 58 to compensate for the air discharged by the damper70. As a result, approximately 90% of air flowing in the work space 22is re-ventilated air and approximately 10% is air freshly taken in.

Hydrogen gas may leak while the operator performs maintenance work onthe maintenance vehicle 110. The leaked hydrogen gas swiftly rises, dueto its low density. Although under certain circumstances the hydrogengas may remain in hollow portions or the like in the vehicle, most ofthe hydrogen gas is swiftly forced out by the flow of air. Then, afterreaching the upper part of the work space 22, the hydrogen gas entersthe air discharge duct 52 from the air discharge device 40 following anoverall flow of air. In this way, hydrogen is diluted by naturalconvection and ventilation in the vehicle maintenance booth 20.

Inside the air discharge duct 52, the hydrogen sensor 80 detects theamount of hydrogen gas at fine sampling intervals (for example, onesecond). The flow inside the air discharge duct 52 is generally madeturbulent under the influence of the fan of the air discharge device 40,and the hydrogen sensor 80 can equally make any air flowing out of theair discharge sections 42, 44, and 46 a detection target. Then, thehydrogen sensor 80 detects hydrogen mixed therein without omission.

In the control device 90, the comparison section 94 compares the amountof hydrogen detected by the hydrogen sensor 80 and the preset thresholdtable 96 to determine the mode of air conditioning operation to beperformed. When, for example, the amount of detected hydrogen is 0 orvery small, as described above, an operation in which approximately 90%of air is circulated is performed. Moderately fresh air can thereby beintroduced also when the work space 22 is heated or cooled withoutlowering efficiency thereof.

Here, assume that a rather larger amount of hydrogen gas has leaked. Inthis case, the hydrogen sensor 80 detects this relatively large amountof hydrogen and outputs detection information to the control device 90.Then, the comparison section 94 refers to the threshold table 96 todetermine that for the detected amount of hydrogen, the air conditioningoperation of the next step must be performed.

FIG. 2 shows an example of the air conditioning operation in this case.This operation is characterized in that, although the amount ofventilation by the air intake device 30 and the air discharge device 40is not changed, the circulation of air is stopped. That is, the damper70 is in a completely open state to smoothly lead air from the airdischarge duct 52 to the exhaust port 54. The damper 72 is in a closedstate to inhibit the circulation of air. Then, the damper 74 is in acompletely open state so that a sufficient amount of air can be taken inthrough the intake.

As a result, leaked hydrogen will be swiftly discharged from the exhaustport 54 to the outside. Therefore, the concentration of hydrogen in thevehicle maintenance booth 20 will be maintained at a sufficiently lowlevel to thereby ensure safety. If a still larger amount of hydrogen isdetected, the operation level of the air intake device 30 and the airdischarge device 40 can be raised while keeping the dampers 70, 72, and74 in the states shown in FIG. 2. Hydrogen can thereby be swiftlyexpelled to the outside to be diluted.

Subsequently, a modification will be described with reference to FIG. 3Aand FIG. 3B. FIG. 3A and FIG. 3B are schematic views showing the vehiclemaintenance booth 20 shown in FIG. 2 from the side of the maintenancevehicle 110. FIG. 3A shows an appearance of air conditioning undernormal conditions and FIG. 3B shows an appearance of air conditioningwhen hydrogen exceeding the set condition is detected.

The ventilation state in FIG. 3A is the same as that described inFIG. 1. That is, a small amount of hydrogen gas is discharged byallowing air to flow from air intake ports 120, 122, and 124 provided onthe floor surface toward air discharge ports 130, 132, and 134 providedon the ceiling wall.

If a large amount of hydrogen is detected, the hydrogen must be swiftlydischarged to the outside. In FIG. 3B, a large amount of air is blownfrom the front toward the rear of the vehicle maintenance booth 20 toswiftly perform the discharge. That is, ventilation from below upwardunder normal conditions is stopped and, instead, air intake ports 140and 142 provided on the front wall of the vehicle maintenance booth 20and air discharge ports 150 and 152 provided on the rear wall are openedand air is blown to the outside by a large fan in a surge. The upperside air intake port 140 and air discharge port 150 are provided nearthe ceiling wall so that, even if hydrogen remains near the ceiling walldue to convection, the hydrogen can be sufficiently expelled. Thus, whena large amount of hydrogen is detected, not only the amount ofventilation, but also the direction of ventilation is changed to realizean efficient discharge, as described above, so that further safety canbe ensured.

If no operator enters the vehicle maintenance booth 20, it is alsoeffective to blow, instead of air, an inert gas (non-inflammable gas)such as nitrogen or helium. That is, by providing a function to blow aninert gas instead of air as a diluent gas or to mix an inert gas withair and also to change at least the ratio of air to the inert gas toflow as a diluent gas, the ratio of the inert gas in the diluent gas maybe increased or the diluent gas may be changed to the inert gas onlywhen an inflammable gas satisfying the set condition is detected. Thisconfiguration has a scope for implementation even if the operator entersthe vehicle maintenance booth 20. For example, by pouring a helium gasfrom a position higher than the operator, it becomes possible to ensuresafe respiration of the operator and also to isolate hydrogen, which isthe lightest and remains rear the ceiling, from air by wrapping thehydrogen with helium, which is the next lightest gas.

Lastly, another modification will be described with reference to FIG. 4.FIG. 4 is a diagram almost identical to FIG. 1 and like referencenumerals are assigned to like components, with repeated descriptionsomitted. A major difference between FIG. 4 and FIG. 1 is that a vehiclemaintenance booth 158 whose ceiling wall 160 is formed in a tilted stateis introduced. The ceiling wall 160 is set in such a way that theceiling becomes higher towards a center point. Then, a thin tube 162 isdisposed upward from the top position of the ceiling wall 160. Also, ahydrogen sensor 164 is mounted inside the thin tube 162.

An air discharge device 170 is mounted on the inside of the ceiling wall160. The air discharge device 170 includes air discharge sections 172,174, 176, and 178, and each of these air discharge sections has an airdischarge port and a fan.

Subsequently, operations according to the configuration shown in FIG. 4will be described. Here, no ventilation is provided when the leakageamount of hydrogen is 0 or very small. However, when hydrogen leakageoccurs, the hydrogen rises due to natural convection and can furtherexit after being led along the slope of the ceiling wall 160 and throughthe thin tube 162. Thus, the vehicle maintenance booth 158 can bemaintained sufficiently safe without providing ventilation even if asmall amount of hydrogen leaks.

Meanwhile, in the thin tube 162 the hydrogen sensor 164 detects theamount of hydrogen at fine sampling intervals. Then, a detection resultis sent to the control device 90 and control based on the thresholdtable 96 is performed. That is, if the amount of hydrogen exceeding thethreshold is detected, the air intake device 30 and the air dischargedevice 170 are activated and also the dampers 70, 72, and 74 areadjusted to swiftly discharge hydrogen to the outside.

1. A handling facility, comprising: a work booth whose periphery issurrounded by partition walls and in which a fuel-cell electric vehiclehaving a fuel cell mounted thereon is termporarily, arrangeablydisposed, the fuel cell using an inflammable gas as a fuel, and in whichhandling work for the fuel-cell electric vehicle is performed, and aforcible gas supply/discharge mechanism that dilutes the inflammable gasleaking out of the the fuel cell into the work booth by supplying adiluent gas to the work booth and discharging gas from the work booth.2. The handling facility according to claim 1, wherein the inflammablegas is a gas lighter than the diluent gas and the gas supply/dischargemechanism supplies the diluent gas from below the work booth and the gasis discharged from above the work booth.
 3. The handling facilityaccording to claim 1, further comprising: an inflammable gas sensordetecting the inflammable gas having leaked into the work booth; and acontrol device controlling a supply or discharge of the gassupply/discharge mechanism in accordance with a detection result of theinflammable gas sensor.
 4. The handling facility according to claim 3,wherein if an inflammable gas satisfying a predetermined condition isdetected, the control device activates the gas supply/dischargemechanism.
 5. The handling facility according to claim 4, wherein aninclined-face structure accumulating the inflammable gas that rises orfalls due to a density difference from the gas filling the work boothunder normal conditions is provided in an upper part or lower part ofthe work booth and the inflammable gas sensor detects the accumulatedinflammable gas.
 6. The handling facility according to claim 3, whereinif an inflammable gas satisfying a predetermined condition is detected,the control device increases supply and discharge amounts by the gassupply/discharge mechanism.
 7. The handling facility according to claim3, wherein the gas supply/discharge mechanism includes a plurality ofsupply ports provided at mutually different positions or a plurality ofexhaust ports provided at mutually different positions, and if aninflammable gas satisfying a predetermined condition is detected, amongthe plurality of supply ports or exhaust ports, the control devicechanges a combination of supply ports or exhaust ports to be activated.8. The handling facility according to claim 3, wherein the gassupply/discharge mechanism comprises a circuit for re-supplying at leasta portion of the gas discharged from the work booth back to the workbooth and if an inflammable gas satisfying a predetermined condition isdetected, the control device suppresses or stops a gas circulation. 9.The handling facility according to claim 1, wherein a vehicle on whichan energy converter is mounted is inspected and maintained in the workbooth. 10-11. (canceled)
 12. A device providing ventilation to workbooth whose periphery is surrounded by partition walls and in which afuel-cell electric vehicle having a fuel cell mounted thereon istemporarily, arrangeably disposed, the fuel cell using an inflammablegas as a fuel, and in which handling work for the fuel-cell electricvehicle is performed, comprising: a forcible gas supply/dischargemechanism that dilutes the inflammable gas leaking out of the fuel cellinto the work booth by supplying a diluent gas to the work booth anddischarging gas from the work booth.